The present invention relates to a hydrostatically operated continuously variable transmission including a hydraulic pump connected to an input shaft and a hydraulic motor connected to an output shaft, the hydraulic pump and the hydraulic motor being coupled in a closed hydraulic circuit.
As disclosed in Japanese Laid-Open Patent Publication No. 61-153057, for example, a hydrostatically operated continuously variable transmission of the type described above has a rotatable cylinder block housing a hydraulic pump and a hydraulic motor. Each of the hydraulic pump and the hydraulic motor comprises an annular array of reciprocable plungers disposed in the cylinder block parallel to the axis of the cylinder block, and a swash plate engaging the outer ends of the plungers and held in an inclined position with respect to the axis of the cylinder block for imparting reciprocating movement to the plungers in response to rotation of the cylinder block.
In the above continuously variable transmission, the plungers of the hydraulic pump and those of the hydraulic motor must be arranged axially of the cylinder block. Therefore, the cylinder block which accommodates these plungers must be axially elongate. The swash plates of the hydraulic pump and the hydraulic motor also have to be positioned close to each other in the cylinder block in the axial direction thereof. These design limitations make it difficult to reduce the axial length of the transmission.